Roland V-Drums TDW-20 Owner's Manual page 14

6. Using the tool included with the TDW-20, turn the
circuit board holders in the LOCK direction to fasten
the TDW-20 in place.
When you've finished installing the TDW-20, double-check to
make sure that it is installed correctly and that the circuit board
holders are in the LOCK position.
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7. Reattach the cover using the eight screws you
removed in step 3.